#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
int max3(int a, int b, int c)
{
    int max = 0;
    max = (a > b) ? a : b;
    max = (max > c) ? max : c;
    return max;
}
int main() {
    int a = 0, b = 0, c = 0, m1, m2, m3;
    scanf("%d %d %d", &a, &b, &c);
    m1 = max3(a + b, b, c);
    m2 = max3(a, b + c, c);
    m3 = max3(a, b, b + c);
    printf("%.2f\n", (float)m1 / (m2 + m3));
    return 0;
}
